1. Field of the Invention
This invention relates to an eye protection device for welder protection equipment, as specifically found in a welder's protective shield or hood.
2. Description of the Prior Art
Eye protection devices for welders are known, for example, from the welder's protective masks and shields sold by Revue Thommen AG. In these devices, a transparent window allows the direct observation of a welding point. The window contains a transparent screen which, as a rule, is provided with a first screen portion which blocks the ultraviolet (UV) emissions and a second screen portion which obstructs infrared (IR) emissions. Additionally, the transparent window contains a welder's protective filter formed of liquid crystals which are operably coupled to a control device, the latter being governed by an electro-optical sensor. When welding emissions are sensed, the control device applies a voltage to the welder's protective filter, whereupon the liquid crystals change their optical characteristics and become impermeable to the welding light. These eye protection devices provide very good results; however, their inherent cost disadvantageously mandates that the corresponding transparent window be made relatively small such that, as a rule, it will fill only a section of the transparent window, while another section is provided with common welder's safety glass. Moreover, the liquid crystals change their optical characteristics depending upon the temperature, displaying slower switching times particularly at lower temperatures such that the desired safety aspects are no longer assured. Additionally, the transparency of these liquid crystals is relatively poor in normal light.